Restarting an erased Mac
I followed the steps to erase my MacBook Pro to giveaway. When I turn it back on it flashes a question mark in a folder. What do I do now to make it useable?
Question marked as
You need to boot into Internet Recovery Mode using Command + Option + R so you can reinstall macOS. Here is an Apple article on how to prepare a Mac for resale or recycling --- the last step is what you need to follow now:
What to do before you sell, give away, or trade in your Mac - Apple Support